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  <title>Document</title>
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<script>
  window.onload = function() {
    function Animal() {
      this.type = 'Anmial';
    }
    Animal.prototype.sayType = function() {
      alert(this.type);
    }
    function Dog(name, age) {
      this.name = name;
      this.age = age;
    }
    Dog.prototype = new Animal();
    Dog.prototype.sayName = function() {
      alert(this.name);
    }
    var jinmao = new Dog('jinmao', 5);
    jinmao.sayType();

  }
</script>
</html>